NAME

vcs, vcsa - virtual console memory

DESCRIPTION

/dev/vcs0 is a character device with major number 7 and minor number 0,
usually of mode 0644 and owner root.tty. It refers to the memory of
the currently displayed virtual console terminal.
/dev/vcs[1-63] are character devices for virtual console terminals,
they have major number 7 and minor number 1 to 63, usually mode 0644
and owner root.tty. /dev/vcsa[0-63] are the same, but using unsignedshorts (in host byte order) that include attributes, and prefixed with
four bytes giving the screen dimensions and cursor position: lines,
columns, x, y. (x = y = 0 at the top left corner of the screen.)
When a 512-character font is loaded, the 9th bit position can be
fetched by applying the ioctl(2) VT_GETHIFONTMASK operation (available
in Linux kernels 2.6.18 and above) on /dev/tty[1-63]; the value is
returned in the unsignedshort pointed to by the third ioctl(2)
argument.
These devices replace the screendump ioctl(2) operations of console(4),
so the system administrator can control access using file system
permissions.
The devices for the first eight virtual consoles may be created by:
for x in 0 1 2 3 4 5 6 7 8; do
mknod -m 644 /dev/vcs$x c 7 $x;
mknod -m 644 /dev/vcsa$x c 7 $[$x+128];
done
chown root:tty /dev/vcs*
No ioctl(2) requests are supported.